﻿Broadband networks are currently able to support high‐bandwidth applications
such as multimedia‐on‐demand (MoD) with a specified Quality‐of‐Service (QoS)
guarantee. Using MoD services, clients can view video programs, listen to audio
programs, and play online‐games anytime, anywhere on the Internet. Multimedia
programs are delivered from a content server in an MoD network to the client's
device (such as a personal computer, notebook, PDA, mobile phone, etc.) when the
service is requested. In the content server, storage capacity and stream transmission
capacity are limited resources. The challenge for the service provider is to obtain the
highest possible revenue from the MoD system with limited resources while
maintaining the QoS to satisfy clients. This thesis addresses this challenge.
Interactive, batch and broadcast are the three common ways of providing MoD
services. Interactive service provides each client with a dedicated stream to transmit
content. With it, the client can use VCR function controls such as pause, forward and
rewind. However, the type of service is expensive and does not scale well with user
population. For batch service, clients who request the same multimedia content
within a batch period are grouped together and served by a single dedicated
transmission stream. Hence, the system can use fewer streams to serve more clients.
However, batch users must wait for their programs to start and are unable to
perform VCR control functions. For broadcast service, the system reserves the
necessary streams for serving content in each broadcast cycle. However, a stream
will be wasted if no requests choose that content within the broadcast cycle.
In this thesis, we study a hybrid MoD system which combines two or three
service types so that we can take advantage of those individual services to improve
system performance and QoS. In addition, we propose a new incentive charging
scheme to encourage clients to select batch service as compensation for the startup
latency and lack of VCR functions on the batch service for a system providing 2 types
of service for clients' selection in each item of stored content. Moreover, we study
different approaches to improving the system performance of the proposed hybrid
MoD system with 3 types of services. Furthermore, a stream reservation scheme is
proposed for hybrid MoD systems with 2 types of service. In this scheme, some
unoccupied streams will be reserved to serve only interactive requests and batch
requests with a large group of batch queues during a stream starving stage in order
to increase the system efficiency. Furthermore, we consider a more realistic model
for MoD systems with the feature of service retrial in which some blocked clients are
allowed to retry the system and request the service again.
Analytical models will be developed for design, analysis and dimensioning of
the proposed hybrid MoD systems and the models will be validated by computer
simulation. Numerical results show that the hybrid MoD system with the stream
reservation scheme can generate higher revenue by serving more concurrent clients
and decrease the average waiting time. And, the hybrid MoD system with service
retrial model can generate higher revenue at the expense of increasing the average
waiting time.